We will study the migration of monocytes to the lung as a hallmark of an effective immune response to C. neoformans. Monocyte recruitment is much less defined than that of neutrophils and lymphocytes, but like them appears to be dependent upon a sequence of dynamic interactions resulting from the expression of a variety of cytokines. The initial adherence of monocytes, which is transient and reversible, targets an inflammatory cell to an area of inflammation. Directed migration, whereby the cell passes through the endothelium and basement membrane, depends on the initiation and maintenance of a chemotactic gradient. Once at the inflamed site, these cells are activated to destroy the microbe and remove injured and degraded endogenous tissues. The molecular signals or specific cytokines involved in the recruitment and activation of these mononuclear cells have not been defined. Recently, studies have defined a supergene family of small inducible protein mediators of inflammation, some of which are monocyte chemoattractant. We will study the expression/regulation of JE/monocyte chemoattractant protein-1 (JE/MCP- 1), which is a specific, potent chemotaxins for monocytes. Or preliminary studies demonstrate JE/MCP-1 is expressed in the lung during the development of C. neoformans induced inflammation. The working hypothesis of this application is that he expression of JE/MCP-1 in the lung os one of the major signals for the recruitment and activation of blood borne monocytes during a C. neoformans-specific pulmonary immune response. JE/MCP-1 production is regulated by cytokine networks involving resident macrophages, specific T lymphocytes and pulmonary parenchymal cells. The specific objectives of this proposal are: 1) To determine and compare the kinetics of JE/MCP-1 production during protective and non-productive inflammatory response to C. neoformans infection; 2) to determine the in vivo role of JE/MCP-1 in an inflammatory response to C. neoformans using a specific neutralizing JE/MCP-1 antiserum; 3) to determine which endogenous cytokines positively or negatively influence the expression of JE/MCP-1 by immune and non-immune pulmonary cells; and 4) To determine if JE/MCP-1 will confer on AM the ability to kill or inhibit the replication of C. neoformans. This proposal will attempt to identify signals capable of initiating and maintaining an effective antimicrobial cellular response to inhaled and aspirated microbes. The proposal will attempt to provide insight regarding exogenous replacement therapy or pharmacologic therapy to manipulate the immune system and thus restore antimicrobial capacity.